Circuit breaker with handle indicating means

ABSTRACT

An improved circuit breaker comprises means operating, when the contacts are welded closed and the cradle is released, to block the trip member or cradle against movement to a reset or relatched position and to maintain the operating handle in the closed position to thereby provide a true external indication of the closed condition of the contacts. The blocking means on the cradle strikes the contact arm in an opening direction when the cradle is released and the contacts are welded whereby if the weld is not firm the striking action will break the weld and open the contacts.

United States Patent [191 Mrenna et al.

CIRCUIT BREAKER WITH HANDLE INDICATING MEANS Inventors: Stephen A.Mrenna; Glenn R.

Thomas, both of Beaver, Pa.

Assigneez- Westinghouse Electric Co orgtion,

Pittsburgh, Pa.

Filed: Nov. 28, 1973 Appl. No.: 419,744

US. Cl. 335/166, ZOO/DIG. 42 Int. Cl. H01h 9/20 Field of Search 355/166;ZOO/DIG. 42;

References Cited UNITED STATES PATENTS Nov. 19, 1974 3,605,052 9/1971Dimond et a1. 335/166 3,614,685 10/1971 Ellsworth et a1 335/166 PrimaryExaminer-Harold Broome Attorney, Agent, or FirmW. A. Elchik [5 7]ABSTRACT An improved circuit breaker comprises means operating, when thecontacts are welded closed and the cradle is released, to block the tripmember or cradle against movement to a reset or relatched position andto maintain the operating handle in the closed position to therebyprovide a trueexternal indication of the closed condition of thecontacts. The blocking means on the cradle strikes the contact arm in anopening direction when the cradle is released and the contacts arewelded whereby if the weld is not firm the striking action will breakthe weld and open the contacts.

3 Claims, 5 Drawing Figures PAH-INTEL NOV 1 9l974 sum 1 or 3 1 FIGSPAIENIE NOV 1 91974 sum 2 or 5 FIG.4

PATENIE auv 191974 sum 30F 5:

1 CIRCUIT BREAKER WITH HANDLE INDICATING MEANS CROSS-REFERENCE TORELATED APPLICATION Certain features of the circuit breaker hereindisclosed are disclosed in the copending patent application of FrancisL. Gelzheiser Ser. No. 419,749, filed concurrently herewith.

BACKGROUND OF THE INVENTION 1. Field of the Invention:

Circuit breakers of the type comprising latch and trip meansautomatically releasable to effect tripping operations and manuallyresettable following tripping operations.

2. Description of the Prior Art:

In the US. Pat. to Bullis, .lr. No. 3,200,217 there is disclosed acircuit breaker having an operating mechanism that is generally similarin operation to the mechanism of the circuit breaker of the subjectinvention. The circuit breaker of this invention is an improvement overthat disclosed in the Bullis, Jr. patent in that the subject breakercomprises means operating, when the contacts are welded closed and thetrip member is released, to block the cradle against movement to aresetting position and to maintain the operating handle in the closedposition to provide a true indication of the closed condition of thecontacts.

The idea of preventing a reset of the trip member or cradle when thecontacts of a circuit breaker are welded closed and of maintaining theoperating handle in the closed position when the contacts are weldedclosed is disclosed in the US. Pat. to Ellsworth et al, No. 3,525,959and to Ellsworth No. 3,614,685. The operating and trip mechanisms in theabove-mentioned Ellsworth et al and Ellsworth patents, however, aresubstantially different from the operating and trip mechanism of thecircuit breaker of the subject invention.

SUMMARY OF THE INVENTION A circuit breaker is provided comprising aninsulating housing and a circuit-breaker mechanism supported in thehousing. The mechanism comprises a stationary contact and a movablecontact. The movable contact is supported on a contact arm. A releasablecradle is pivotally supported in proximity to one end thereof andlatched, at the other end thereof, on trip means. An operating spring issupported at one end thereof on the contact arm and at the other endthereof on the cradle. An operating member is operatively connected tothe contact arm and extends through an opening in the front of thehousing to permit manual operation of the breaker. With the cradle inthe latched position, the operating member is manually operable betweenopen and closed positions to operate the spring and contact arm tothereby move the movable contact arm between open and closed positions.Upon the occurrence of overload current conditions above a predeterminedvalue the trip means releases the cradle whereupon the spring moves thecradle to a tripped position and the contact arm to the open position.Following movement of the cradle to the tripped position, the operatingmember is manually movable to the open position during which movementthe operating member engages the cradle to move the cradle back to thelatched position. Blocking means on the contact arm engages blockingmeans on the cradle to prevent movement of the cradle to the latchedposition when the contacts are welded closed and the cradle has beenmoved toward the tripped position. Following an attempt to reset thecradle, when the contacts are welded closed, the spring and mechanismwill move the operating member back to the closed position upon releaseof the operating member by an operator, thereby providing a visualindication that the contacts are in the closed position. The blockingmeans on the cradle is bent-over tab part that also serves to strike thecontact arm in an opening direction when the cradle is released and thecontacts are welded whereby if the weld is not a firm weld the strikingaction will break the weld and permit opening movement of the contactarm.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side sectional view of acircuit breaker embodying principles of this invention. The circuitbreaker is shown in the closed position;

FIG. 2 is a view similar to FIG. I with the breaker shown in the off oropen position; 1

FIG. 3 is a view similar to FIG. 1 with the breaker being shown in thetripped open position;

FIG. 4 is a view similar to FIG. 1 with the breaker being shown in thetripped position when the contacts have been welded closed; and,

FIG. 5 is a partial view similar to FIG. 1 illustrating the position ofparts when the breaker has tripped with the contacts welded closed andan attempt is made to reset the cradle.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, thereis shown a circuit breaker 9 comprising an insulating housing thatcomprises a molded insulating side compartment part I] and a moldedinsulating side cover part 13 (FIG. 5) secured together by means of fourrivets 15 (FIG. 1). A circuit-breaker mechanism, indicated generally at17, is supported in the housing ll, 13. The mechanism 17 comprises astationary supporting frame 19 fixedly supported in the housing on thehousing part 11. The mechanism 17 also comprises a stationary contact21, a movable contact 23, and trip means indicated generally at 25.

The stationary contact 21 is welded or otherwise fixedly secured to aline tenninal 27 that extends out through an opening in the bottom ofthe housing ll, 13. The movable contact 23 is fixedly secured to one 7end of a contact arm 29. The contact arm 29, at the upper end thereof,is provided with a depression 31 therein. A molded insulating part 33 ofan insulating operating member 35 engages the contact arm 29 in thedepression 31 to provide an operative driving connection between theoperating handle 35 and the contact arm 29. The operating member 35 ismolded with a pair of pin parts 37 at the opposite sides thereof whichfit into bearing openings in the housing parts 11 and 13 to support theoperating member for pivotal movement on the housing ll, 13. Theoperating member 35 comprises a handle part that extends through anopening at the top of the housing 11, 13, to enable manual operation ofthe circuit breaker. A cradle 41 (FIGS. 1-3) is supported at one endthereof for pivotal The trip means comprises an elongated bimetal member49 secured, in proximity to its upper end, to a bent-over tab part 51 ofthe frame 19. A flexible conductor 53 is connected at one end thereof tothe upper end of the bimetal 49 and at the other end thereof to aconductor 55 that extends through an opening 57 in the housing 11, 13and is part of a solderless terminal connector 59 that is externallyaccessible and supported on the housing 11, 13 in a well-known manner.Another flexible conductor 61 is secured at one end thereof to the lowerend of the bimetal 49 and at the other end thereof to the contact arm 29to electrically connect the contact arm 29 with the bimetal 49.

The circuit through the circuit breaker 9 extends from the line terminal27, through the stationary contact 21, the movable contact 23, thecontact arm 29, the flexible conductor 61, the bimetal 49, the flexibleconductor 53, the conductor 55, to a conducting line (not shown) thatwould be connected to the conductor 55 by means of the solderlessterminal connector 59 at an installation.

The circuit breaker 9 may be manually operated to open and close thecontacts by operation of the insulating operating handle member 35.Movement of the operating member clockwise from the closed or onposition (FIG. 1) to the open or off position (FIG. 2) carries the upper'end of the contact arm 29 to the left of the line of action of thespring 43 whereupon the spring 43 acts to move the contact arm 29 with asnap action to the open position (FIG. 2). Movement of the operatingmember 35 in a counterclockwise direction back to the closed positionmoves the upper end of the movable contact arm 29 to the right of theline of action of the spring 43 whereupon the spring acts to move thecontact 29 to the closed position (FIG. 1) with a snap action.

The trip device 25 comprises the bimetal 49, a magnetic yoke 63 and amagnetic armature 65. The yoke 63 is a generally U-shaped member securedto the bimetal 49 at the bight portion of the yoke 63 with the oppositelegs thereof facing the armature 65. The magnetic armature 65 is securedto a supporting spring 67 that is secured, at its lower end, to thebimetal 49 whereby the armature 65 is supported on the bimetal 49 bymeans of the spring 67. The armature 65 has a window opening 71 therein.The one end of the cradle 41 is disposed in the window opening 71 andengages the latch surface 73 of the armature 65 in the latched positionshown in FIGS. 1 and 2.

Upon the occurrence of an overload current above a first predeterminedvalue, the bimetal 49 becomes heated and deflects to the right as seenin FIG. 1 to effect a time delayed thermal tripping operation. Thearmature 65, which is supported on the bimetal 49 by means of the spring67, is carried to the right with the bimetal to release the cradle 41.When the cradle 41 is released, the spring 43 acts to rotate the cradleclockwise onthe post 42 about an axis 77 until this motion is arrestedby the engagement of the cradle 41 with a molded housing part 79 of thehousing 11, 13. During this movement, the spring 43 moves the contactarm 29 to the open position and the operating member 35 to anintermediate position intermediate the on" and off positions to providea visual indication that the circuit breaker has tripped open. Thetripped position of the parts is shown in FIG. 3.

Before the contacts can be closed following an automatic trippingoperation it is necessary to reset and relatch the mechanism. This isaccomplished by moving the operating member 35 clockwise from theintermediate position to a position slightly beyond the full open or ofposition. During this movement, due to the engagement of a downwardlyextending portion 79 of the operating member 35 with the bent-overextension 47 of the cradle 41 (FIG. 3), the cradle 41 is movedcounterclockwise about the axis 77 until the end of the cradle 41 isagain latched in the window opening 7-] of the armature on the latchsurface 73 (FIG. 2). Following a resetting operation the circuit breakercan be manually operated in the same manner as was hereinbeforedescribed.

The circuit breaker is magnetically tripped automatically andinstantaneously in response to overload currents above a secondpredetermined value higher than the first predetermined value. Upon theflow of the overload current through the bimetal 49, magnetic flux,which is induced around the bimetal, takes the path of least reluctancethrough the magnetic yoke 63, across an air gap and through the armature65. When an overload current above the second predetermined valueoccurs, the pull of the magnetic flux is of such strength that thearmature 65 is attracted to the magnetic yoke 63 whereupon the spring 67flexes pennitting the armature to move to the right to release thecradle 41 whereupon the circuit breaker is tripped open in the samemanner as was hereinbefore described with regard to the thermal trippingoperation. Following a magnetic tripping operation the circuit breakeris reset and relatched in the same manner as was hereinbefore described.

The circuit breaker 9 comprises means for maintaining the operatingmember 35 in the onT or closed position when the cradle 41 is releasedwith the contacts 21, 23 welded in the closed position, and blockingmeans for preventing a resetting operation of the cradle 41 whereby theexternal handle of the operating member 35 will provide a trueindication that the contacts I 21, 23 are closed.

As can be understood with reference to FIG. 4, when the contacts 21, 23are welded closed and an overload occurs, the trip means 25 will releasethe cradle 41 and the spring 43 will move the cradle 41 clockwise aboutthe axis 77 toward the tripped position during which movement abent-over tab 81 on the cradle 41 strikes the contact arm 29 in openingdirection whereby if the weld between the contacts 21, 23 is not a firmweld this striking action will break the weld and the parts will move tothe tripped open position seen in FIG. 3. As can be understood withreference to FIG. 4, the cradle 41 is a flat sheet-metal member and thetab 81 is bent over to protrude in the direction out of the paper asseen in FIG. 4 so that the tab 81 is disposed to engage the sheet-metaltype contact arm 29 to strike the contact arm 29 in an openingdirection. As can be seen in FIG. 4, when the contacts 21, 23 are weldedclosed and the tab 81 does not break the weld, movement of the cradle 41is arrested in the position shown inFIG.

4. In this position, the geometry of the parts and the force of thetension spring 43 are such as to maintain the operating member 35 in theon or closed position toprovide a true external visual indication thatthe contacts are closed. As can be understood with reference to FIG. 5,when the contacts 21, 23 are welded and an attempt is made to reset thecradle 41, the operating member 35 is manually pivoted clockwise towardthe off position during which movement the contact arm 29 is moved tomove a blocking surface 85 into engagement with the tab 81 to blockfurther resetting movement of the operating member 35, contact arm 29and cradle 41 with the parts being blocked in the position seen in FIG.5 so that if the weld between the contacts 21, 23 is not broken by thisaction the operating member 35 cannot be moved further toward theresetting position and the movement of parts will stop in the positionseen in FIG. 5 without movement of the cradle 41 to the reset orrelatched position. Upon release of the operating member 35 following anattempt to reset the cradle 41 when the contacts 21, 23 are weldedclosed the spring 43 and mechanism will move the parts back to theposition seen in FIG. 4 with the operating member 35 beng moved back tothe on or closed position to thereby provide a visual indication of theclosed condition of the contacts. Thus, an operator cannot reset thebreaker and the operating member 35, in the closed position, provides anexternal true indication that the contacts are in the closed position.

We claim:

1. A circuit comprising an insulating housing having an opening in thefront thereof, a circuit-breaker mechanism supported in said housing,said mechanism comprising a stationary contact, a movable contact, acontact arm supporting said movable contact, trip means, a releasablecradle, means pivotally supporting said cradle in proximity to one endthereof, said cradle at the other end thereof being latched on said tripmeans, an operating spring supported at one end thereof on said contactarm and at the other end thereof on said cradle, an operating memberoperatively connected to said contact arm and extending through saidopening to permit manual'operation of said circuit breaker, with saidcradle in the latched position said operating member being manuallymovable between open and closed positions to operate said spring andsaid contact arm to thereby move said contact arm between open andclosed positions, upon the occurrence of an overload current above apredetermined value said trip means releasing said cradle and saidspring moving said cradle to a tripped position and said contact arm tothe open position, following movement of said cradle to said trippedposition said operating member being manually movable to the openposition during which movement said operating member engages said cradleto move said cradle back to the latched position, blocking means on saidcontact arm engaging blocking means on said cradle to prevent movementof said cradle to the latched position when said contacts are weldedclosed and said cradle has been moved toward the tripped position, andsaid blocking means on said cradle striking said contact arm in anopening direction when said cradle is released and said contacts arewelded closed whereby if the weld of said contacts is not a firm weldthe striking action can break the weld to permit movement of saidcontact arm to the open position.

2. A circuit breaker according to claim 1, said mechanism maintainingsaid operating member in the closed position when said contacts arewelded closed and said cradle has been moved toward the trippedposition, said mechanism returning said operating member to the closedposition upon release by an operator when an attempt is made to resetsaid cradle with said contacts welded closed to thereby provide a trueindication of the closed condition of said contacts.

3. A circuit breaker according to claim 2, said cradle being asheet-metal type member, and said blocking means on said cradle being abent-over tab bent over to a position where said blocking means on saidcradle will strike said contact arm in anopening direction when saidcradle is released and said contacts are welded closed.

1. A circuit comprising an Insulating housing having an opening in thefront thereof, a circuit-breaker mechanism supported in said housing,said mechanism comprising a stationary contact, a movable contact, acontact arm supporting said movable contact, trip means, a releasablecradle, means pivotally supporting said cradle in proximity to one endthereof, said cradle at the other end thereof being latched on said tripmeans, an operating spring supported at one end thereof on said contactarm and at the other end thereof on said cradle, an operating memberoperatively connected to said contact arm and extending through saidopening to permit manual operation of said circuit breaker, with saidcradle in the latched position said operating member being manuallymovable between open and closed positions to operate said spring andsaid contact arm to thereby move said contact arm between open andclosed positions, upon the occurrence of an overload current above apredetermined value said trip means releasing said cradle and saidspring moving said cradle to a tripped position and said contact arm tothe open position, following movement of said cradle to said trippedposition said operating member being manually movable to the openposition during which movement said operating member engages said cradleto move said cradle back to the latched position, blocking means on saidcontact arm engaging blocking means on said cradle to prevent movementof said cradle to the latched position when said contacts are weldedclosed and said cradle has been moved toward the tripped position, andsaid blocking means on said cradle striking said contact arm in anopening direction when said cradle is released and said contacts arewelded closed whereby if the weld of said contacts is not a firm weldthe striking action can break the weld to permit movement of saidcontact arm to the open position.
 2. A circuit breaker according toclaim 1, said mechanism maintaining said operating member in the closedposition when said contacts are welded closed and said cradle has beenmoved toward the tripped position, said mechanism returning saidoperating member to the closed position upon release by an operator whenan attempt is made to reset said cradle with said contacts welded closedto thereby provide a true indication of the closed condition of saidcontacts.
 3. A circuit breaker according to claim 2, said cradle being asheet-metal type member, and said blocking means on said cradle being abent-over tab bent over to a position where said blocking means on saidcradle will strike said contact arm in an opening direction when saidcradle is released and said contacts are welded closed.